osx man page for newgrp

NEWGRP(1)						    BSD General Commands Manual 						 NEWGRP(1)

NAME
     newgrp -- change to a new group

SYNOPSIS
     newgrp [-l] [group]

DESCRIPTION
     The newgrp utility creates a new shell execution environment with modified real and effective group IDs.

     The options are as follows:

     -l      Simulate a full login.  The environment and umask are set to what would be expected if the user actually logged in again.

     If the group operand is present, a new shell is started with the specified effective and real group IDs.  The user will be prompted for a
     password if they are not a member of the specified group.

     Otherwise, the real, effective and supplementary group IDs are restored to those from the current user's password database entry.

EXIT STATUS
     The newgrp utility attempts to start the shell regardless of whether group IDs were successfully changed.

     If an error occurs and the shell cannot be started, newgrp exits >0.  Otherwise, the exit status of newgrp is the exit status of the shell.

SEE ALSO
     csh(1), groups(1), login(1), sh(1), su(1), umask(1), group(5), passwd(5), environ(7)

STANDARDS
     The newgrp utility conforms to IEEE Std 1003.1-2001 (``POSIX.1'').

HISTORY
     A newgrp utility appeared in Version 6 AT&T UNIX.

BUGS
     Group passwords are inherently insecure as there is no way to stop users obtaining the crypted passwords from the group database.	Their use
     is discouraged.

BSD
								   May 23, 2002 							       BSD